1. Field of the Invention
The present invention relates generally to the field of cooling systems for computers housed within an enclosure or chassis. More particularly, the invention relates to a system for providing convective cooling of components within a computer chassis and for reducing transfer from the chassis of acoustical noise resulting from operation of the cooling system.
2. Description of the Related Art
A wide range of configurations are known and are commercially available for computer systems, including desktop computers, servers, work stations, and the like. In general, such systems include a primary console or cabinet supporting and housing various system components, including a signal processor, memory circuitry, hard disk drives, floppy drives, CD ROM drives, power supplies, and so forth. During operation of the computer system, significant heat may be generated by the components, particularly by the signal processing circuitry and drives. To avoid excessive temperatures which could cause damage to the system components, it is commonplace to provide fans for drawing a flow of air into and through the console chassis to convectively cool the components.
Conventional fan cooling systems for computers typically include a small DC motor directly coupled to a rotary fan. Depending upon the cooling requirements, several such fans may be included, such as for directing a flow of cooling air over signal processing circuitry, as well as through power supply circuitry. Inlet apertures are provided in the chassis to facilitate the circulation of air over the circuit components. The motor and fan sets are generally supported by either external mounting structures, or by plates which are secured directly to an interior peripheral wall of the chassis or to mounting tabs within the chassis. When the system is operating, the fan motor is energized by the power supply to force the desired air flow over the circuit components. Control elements may also be included, such as thermistors, for regulating the speed of the fan based upon sensed temperature.
While such conventional cooling techniques do provide adequate cooling in many situations, they are not without drawbacks. For example, the operation of cooling fans can generate significant levels of acoustical noise which may be transmitted to the operator through the apertures in the chassis provided for entry of cooling air. This is particularly true where fan assemblies are provided directly adjacent to an outer wall of the chassis, or in an external mounting structure. Moreover, noise due to turbulent flow of air into and through the chassis can result from operation of large cooling fans as may be required in more powerful systems. Also, conventional arrangements for cooling of the computer system components, such as CPUs, may not direct flow adequately over the circuitry, resulting in an unacceptable level of heating, particularly in warmer climates and higher altitudes.
In addition to the foregoing drawbacks, cooling systems for computer components often do not realize advantageous synergies between separate cooling structures within the systems. In particular, in addition to requiring cooling for signal processing circuitry and power supplies, many systems may require additional cooling for disk drives, floppy drives, CD drives, and so forth. Where such additional cooling is required, a supplementary cooling fan structure is generally provided. In certain known systems, this cooling fan assembly directs flow from an internal region of the chassis around the drives. However, the resulting flow rate of cooling air and the temperature difference across the drives may still remain insufficient for adequate cooling.
There is a need, therefore, for an improved technique for cooling components of computer systems housed within a system chassis. In particular, there is a need for an improved cooling system which reduces the amount of acoustical noise transmitted from the system chassis during operation of cooling fans and their drive motors. There is also a need for a cooling system capable of directing or orienting air flow to provide a more laminar stream and a direct path for cooling air both into and from cooling fans. Such a technique would advantageously afford additional cooling for system components such as drives.